1. Field of the Invention
This invention relates to plastic caps for dispensers, and especially to flip-top-type plastic caps for containers dispensing products such as shampoo, lotion, liquid soap, and condiments.
2. Description of the Prior Art
A large variety of flip-top-type plastic caps are known. Such caps generally consist of a base with a pivoting cover, the base having an axial dispensing outlet, and the cover including a closure to stopper the outlet.
To date, no known design permits full operation of the cap with a single thumb or finger. Such operation would enable one to open the cap and dispense the container contents using only one hand, thereby ensuring sanitary and efficient handling of the dispenser.
Cap designs of the prior art require more than one thumb or finger to operate. Since flip top caps tend to accumulate material from the container along the dispensing path, the placement of the thumb or fingers in the region of the dispensing path is both inconvenient and unsanitary. See for example Bush, U.S. Pat. No. 4,666,068, May 19, 1987.
In some cap designs, the closure mechanism is operated by projections which are engageable by a thumb or finger. These are efficient and sanitary in some cases, but cannot be manufactured economically, and the containers are difficult to stack and to maintain closed during shipping, handling and storage. See for example Jenks, U.S. Pat. No. 2,111,186, Mar. 15, 1938.
The prior art cap designs are most easily operated by the use of more than one thumb or finger. In some cases, two hands are needed to open the cap and dispense the product, a serious problem when only one hand is available. This problem is especially evident in child resistant designs, for example Gach, U.S. Pat. No. 4,236,653, Dec. 2, 1980, where safety closures are important. There is therefore a distinct need for an efficiently designed flip-top-type cap which can be opened and closed with one finger and fully operated with one hand.